There is a need within the packaging industry to stack product of various sizes and pack patterns. This must be done reliably at high speeds. Quick change from one size to another within a specified range of product sizes is also required. Product that is incorrectly oriented must be prevented from entering the stacker or a machine jam could result. If a jam does occur, the product stacker design must have the ability to quickly clear and restart production to keep downtime to a minimum. The machine must have the ability to buffer incoming product while stacked product is unloaded from the machine.